BoilerFaultCodesTechnical description
Insufficient water pressure or poor flow in system. Check pressure gauge reading; if low restore pressure (see 2.2.1) then reset as described in code 01. If the pressure gauge reading is correct check for sufficient primary water movement or correct operation of flow switch. Reset as described for code 01.
What causes this fault?
This fault occurs when the boiler detects there isn't enough water volume or pressure to safely transfer heat away from the burner. The most common reason is a simple leak or air in the radiators causing the pressure to drop, but it can also happen if the internal pump fails to move the water around. Without this constant flow, the boiler shuts down to prevent the internal components from overheating.
This issue often appears in autumn when the heating is turned back on for the first time, as small leaks over the summer can gradually drain the system's pressure.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.